What pbonsalb said, any of the major manufacturers will make a good product, the main concern would be the quality of the welds and clamps. I'm sure they're all very similar in this regard so just get the cheapest ones. I just picked up a slightly used set of MS ones last week on the forum.

As I'm sure you know, after deleting the cats the car will throw a code for increased emissions. You can purchase something like the akra delete-r which will just remove the code, or you can go with a full ECU tune. Check out this link:

Any of the test pipes able to clamp the original cats back up for smog testing, and then swapping back to the test pipe?
Most seem to cut the stock pipe pretty close to the cat and I'm not sure there's enough tubing on the stock piece to clamp back on.

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Let me get this straight... You are swapping out parts designed by some of the top engineers in the world because some guys sponsored by a company told you it's "better??" But when you ask the same guy about tracking, "oh no, I have a kid now" or "I just detailed my car." or "i just got new tires."

Any of the test pipes able to clamp the original cats back up for smog testing, and then swapping back to the test pipe?
Most seem to cut the stock pipe pretty close to the cat and I'm not sure there's enough tubing on the stock piece to clamp back on.

That's pretty much it, there's not much metal to clamp back onto without welding.

Any of the test pipes able to clamp the original cats back up for smog testing, and then swapping back to the test pipe?
Most seem to cut the stock pipe pretty close to the cat and I'm not sure there's enough tubing on the stock piece to clamp back on.

Aus, I have seen a few that were re-welded. If it is a good clean cut with a good welder I doubt anyone would be hard pressed to tell you had the xpipe cut.

I'm lucky found a used one for $150 awhile back and cut that one up while keeping the one that came on the car.